| Rescue Knives | | | | locked open position. |
| Blade Style | | | | Another option is the thumb stud, which can be |
| Rescue Knife designs often feature a modified | | | | right or left handed or ambidextrous. This may be |
| Sheep Foot or Wharncliffe style blade. Emergency | | | | permanently riveted to the blade as most |
| procedures may involve cutting through a | | | | ambidextrous thumb studs are, or removable to |
| jammed seat belt in the aftermath of a car crash. | | | | allow for right or left handed positioning. The |
| Clothing may also have to be cut through in order | | | | so-called ambidextrous thumb lug is attached to |
| to free a victim or to gain venous access. Cutting | | | | the back edge of the blade instead of the flat |
| through fibrous materials in such close proximity | | | | surface of the blade. The disadvantage of having |
| to the casualty is much safer if the knife being | | | | a thumb stud or lug attached to the blade is that |
| used has a blunt or rounded tip. | | | | it may interfere with the cutting activity when |
| The Emerson Knives US Navy Search and | | | | using the knife. If the thumb stud is positioned too |
| Rescue Knife (SARK) has a partially serrated | | | | far along the blade it will compromise the blades |
| blade with a Wharncliffe style blade, similar to the | | | | usefulness, whilst if positioned too close to the |
| Eickhorn Pocket Rescue Tool PRT XII. The | | | | handle, it will be difficult in practical use. |
| Spyderco Atlantic Salt and Rescue 93 mm knives | | | | The blade opening, thumb hole-pull also allows |
| are blunt-ended Sheep Foot style blades | | | | one-handed opening. The cut-out portions of the |
| A serrated edge increases the effective cutting | | | | blade are different shapes depending on the |
| edge length by up to 24%. The sharpened | | | | manufacturer. There are many variations such as |
| recesssed curve has more linear cutting surface | | | | the Spyderco Round Hole, the Tool Logic oval |
| than a straight edge. Edge retention is also | | | | hole, the Byrd Knives, tear-drop shaped hole and |
| greater because cutting is started by the | | | | the Leatherman oblong shaped thumb hole pull. |
| serrations' tips, easing the workload on the | | | | The size of the thumb opening hole in Spyderco |
| recessed edges, and protecting the sharp inside | | | | knives is increased to 14 mm diameter in military |
| cutting curves which wear less over time. | | | | and rescue models, an allowance for gloved |
| Seat Belt Cutter | | | | hand-use. Thumb hole sizes in Spyderco knives |
| A Secondary blade or seat belt cutter is a safety | | | | varies from 11 mm in the Lava and Kopa knives, |
| feature for use when cutting in close proximity to | | | | 12 mm in the Police knife, 13 mm in the UK |
| a living person. This may involve cutting through a | | | | Penknife and 14 mm. In the Assist and Atlantic |
| jammed seat belt restraint or cutting through | | | | Salt knives. The Spyderco Assist Knife has an |
| clothing. Incorporated into a slot in the handle it is | | | | added 'Cobra Hood', which is a raised border along |
| used by positioning the fixed material within the | | | | the top edge of the spine cusp above the thumb |
| slot and pulling the knife in the opposite direction. | | | | hole. The 'Cobra Hood' makes blade opening easier |
| The 'Rescue Hook' is a design variation where the | | | | when the thumb is not fully engaged in the thumb |
| blade tip has a blunt outer surface, and a | | | | hole, for instance when the user is wearing gloves. |
| sharpened inner crescent shaped edge. Many | | | | Holding the knife in the palm of the hand at the |
| manufacturers have their own variants of this | | | | base of the fingers, grasp the handle with the tips |
| design. An example is the Eickhorn Pocket rescue | | | | of the fingers, place the pad of the thumb in the |
| Tool PRT XI | | | | thumb hole, then slide the blade away from the |
| One-Handed Opening | | | | handle using the thumb. |
| The Emerson wave Hook, invented by Emerson | | | | Window Puncher / Glass Breaker |
| Knives provides a solution to the one-handed | | | | The window puncher or glass breaking stud is a |
| opening of a folding knife. This opens the blade | | | | pointed, cylindrical protrusion mounted on the |
| when the knife is withdrawn from a pocket. | | | | handle, usually at the opposite end to the blade |
| Grasping the end of the handle between | | | | pivot. It is made of tungsten carbide, effective at |
| forefinger and thumb, the knife is drawn out and | | | | breaking toughened glass due to its diamond-hard |
| backwards. The hook protruding from the blade | | | | nature. The Spyderco Assist knife has a |
| back catches on the pocket and opens the blade. | | | | retractable carbide tip, which is activated by |
| If the knife is drawn out and backwards in one | | | | squeezing the blade into the handle. |
| complete motion, the blade opens fully to the | | | | |